Two days later, former President Obama took credit for the nation's soaring economy and bashed President Trump before a crowd of only 2,000, ABC News reported. The venue, the Cox Pavilion at the University of Nevada, Las Vegas, seats between 2,154 and 3,286 people, depending on its configuration.

"When you hear all this talk about economic miracles, remember who started it," Obama told his audience. "I hope people realize there's a pattern that every time [Republicans] run things into the ground and we've got to clean it up."

A UNLV spokesperson told Fox News she was unaware why the state's Democratic Party chose not to hold the rally at the adjacent Thomas & Mack Center, which she confirmed could seat between 3,600 and 19,000.

A new NBC News-Wall Street Journal poll released Sunday showed Trump’s approval ratings have increased to their highest point yet: 47 percent, with 49 percent disapproving. The number is higher than President Barack Obama's 45 percent approval rating at the same time in his first term, October 2010.

Meanwhile, the Trump campaign announced that it had received more than 100,000 requests for tickets for its packed rally in Houston Monday night in support of incumbent Republican Sen. Ted Cruz, who is now polling several points ahead of rival Texas Rep. Beto O'Rourke.

Thousands tailgated before the event on Monday night in a gameday-style atmosphere in the city, which leans Democratic in a deeply red state.

Kersten Buck, 25, and her fiance Clayton Dupree, 25, sit on an inflatable couch as they wait for a President Donald Trump rally for Sen. Ted Cruz at the Toyota Center on Monday, Oct. 22, 2018, in Houston. (Godofredo A. Vasquez/Houston Chronicle via AP)

However, there were some indications that Trump may not be inspiring as much early in-person voting as Republican candidates might want. Only 435 people in Elko County, Nevada voted on Saturday despite Trump's rally that day, including 104 Democrats and 250 Republicans.

Early voting results in Nevada were generally favorable to Democrats, but experts have told Fox News it's too early to say any trend has developed there.